Air jet spinning machines with corresponding spinning units are known in the state of the art, and serve the purpose of producing a yarn from an elongated fiber composite. Here, the outer fibers of the fiber composite are, with the assistance of a vortex air flow generated by the air nozzles within the vortex chamber in the area of the inlet mouth of the yarn formation element, wound around the internal core fibers, and ultimately form the winding fibers that determine the desired strength of the yarn. This creates a yarn with a genuine twist, which may be ultimately led away through a draw-off channel from the vortex chamber, and wound up, for example, on a sleeve.
In general, within the meaning of the invention, the term “yarn” is understood to be a fiber composite, for which at least one part of the fibers is wound around an internal core. Thus, this comprises a yarn in the conventional sense, which may be processed into a fabric, for example with the assistance of a weaving machine. However, the invention also relates to air jet spinning machines, with the assistance of which so-called “roving” (another name: coarse roving) may be produced. This type of yarn is characterized by the fact that, despite a certain strength, which is sufficient to transport the yarn to a subsequent textile machine, it is still capable of drafting. Thus, the roving may be drafted with the assistance of a drafting device, for example the drafting system, of a textile machine processing the roving, for example a ring spinning machine, before it is ultimately spun.
In the production of a yarn from synthetic fibers, such as polyester, or mixtures of natural and synthetic fibers, deposits on the surface of the yarn formation element arise. The production of synthetic fibers comprises a so-called “preparation of continuous fibers” during the production process. Preparation agents, usually oils with various additives, are applied at the continuous fibers; this enables a treatment such as, for example, drafting the continuous fibers at high speeds. Such preparation agents sometimes adhere to the synthetic fibers even during the further treatment, and lead to impurities in the air jet spinning machine. The fibers fed to the air jet spinning machine in the form of a fiber composite are typically fed by a pair of delivery rollers of the spinning nozzle. The pair of delivery rollers may match a pair of output rollers of a drafting system. The drafting system that is used serves the purpose of the refinement of the advanced fiber composite prior to entering the spinning nozzle.
Typically, a fiber guide element is arranged in the entrance area of the spinning nozzle; through this, the fiber composite is led into the spinning nozzle and finally in the area of the yarn formation element. As yarn formation elements, the majority of spinning units are used with an internal draw-off channel. At the top of the yarn formation element, compressed air is introduced through the housing wall of the spinning nozzle in such a manner that the specified rotating vortex air flow arises. As a result, individual external fibers are separated from the fiber composite leaving the fiber guide element and are turned over through the top of the yarn formation element. In the further process, these removed fibers rotate on the surface of the yarn formation element. Following this, through the forward movement of the internal core fibers of the fiber composite, the rotating fibers are wound around the core fibers and thereby form the yarn. However, through the movement of the individual fibers over the surface of the yarn formation element, deposits also form on the yarn formation element because of adhesions on the fibers from the production process. For the same reasons, deposits may also occur on the surface of the interior of the spinning nozzle or the fiber guide element. These adhesions lead to deterioration of the surface condition of the yarn formation element, and cause a deterioration in the quality of produced yarn. Therefore, the regular cleaning of the affected surfaces is necessary in order to maintain the consistent quality of the spun yarns.
The surfaces of the yarn formation element, the interior of the spinning nozzle and the fiber guide element may be cleaned manually through a periodic disassembly of the yarn formation element, but this leads to a substantial maintenance effort, coupled with a corresponding interruption in operations.
By contrast, EP 2 450 478 discloses a device that enables an automatic cleaning without stopping the machine. For this purpose, during a cleaning process, an additive is mixed with the compressed air used for the formation of the vortex air flow within the spinning nozzle. The additive is guided through the compressed air on the yarn formation element, and results in the cleaning of the surface of the yarn formation element.
However, with the solution specified above, it is disadvantageous that the yarn provided with the additive during the cleaning process generally does not correspond to the quality requirements, since the yarn properties are negatively affected by the quantity of additive (which is not insignificant) along with the absorbed impurities.